Speed-responsive device



Aug. 29, 1939.

c. l. McNll. Er' AL SPEED-RES PONS IVE DEVICE Filed May 5, 1936 Patented Aug. 29, 1939 yUNITED STATES PATENT ori-ICE SPEED-RESPONSIVE DEVICE Application May 5, 1936, Serial No. 78,024

1 Claim.

This invention relates to control apparatus, and particularly to the control of fluid actuated apparatus in accordance with the rate of movement of a rotary part associated with the device to be controlled. y

It is an object of this invention to provide con-g trol means for speed regulation and more particularly for internal combustion engines that is responsive to changes in speed of the engine so as to maintain the desired predetermined mixture strengths.-

In practicing the invention herein disclosed the essential factors include a servo-motor having piston and valve elements, or their equivalents, in'

combination with a speed responsive element adapted to control operation of the servo-motor, .butin such manner that all eleme ts of the speed responsive mechanism remain'mec anically separatefrom the piston or equivalent element ofthe servo-motor at all times, so that there is no possibility of movements of the said piston being transmitted back to the speed responsive mechanism. It is accordingly an object of the invention to provide novel means for inter-relating a speed responsive mechanism with a servo-motor whereby the former may control the amount of movement-that is, length of strokeof the latter4 while at the same time being free from the servo-motor to such an extent that the piston movements of the latter do not produce corresponding movementsA of the speed responsive or governing mechanism.

vA further object of the invention is to provide a -servo-motor of the type in which the valve mechanism cooperates with the piston-containing cylinder of the servo-motor in such manner as to adjustably locate the outlet for the fluid which acts upon the piston of the unit, the relationship between the two being such as to permit flow of uid through said outlet only until the piston has reached a position of equilibrium inv which the pressures on the opposing sides thereof are equal. l

Another object of the invention is to substitute for the single oil pressure chamber type of servomotor, a double chamber concept, involving the.

development of balanced oil pressures-in-ehambers on opposite sides fof the piston; such substitution resulting in` the following advantages:

1. The force available for doing workbecomes forward and return movements, regardless of length of movement.

4. The static setting may be held constant notwithstanding changes in oil pressure.

5. An increase in operating range, rendering the unit eective for any oil pressure value, however low. Other advantages, as well as other objects of the invention, will be apparent on examination of the following description, when read with reference to-the accompanying drawing wherein:

Fig. 1 is a view in section of a device embodying the invention;

Fig. 2 is a kview in'section along the line 2 2 of Fig. 1 with the piston and rod omitted; and

Fig. 3 is a view in section along the line 3 3 of Fig. 1.

'Ihe parts (not shown) to be associated with and driven by, the piston rod 8' maybe operatively connected with a device for changing the amount of air or fuel admitted to the combustion chambers of an engine, or to a device for changing the percentage of fuel in the combustible mixture, or any equivalent device for governing the energy input of apower plant whos'edrive shaft y thereof. At its inner end, rod 8 terminates ina piston II, but on lthe opposite side of the piston there is a second piston rod 9 which does no work but serves to reduce the exposed surface of the piston, thus creating equal effective areas on both -sides of the piston. The oil supply line 2| has taps 22 and 23 to the opposing chambers 24 and 25, of which the piston I i forms the dividing wall,

together with its apron I 3 slldable in slo't I4 to permit, when moved from the position indicated in Fig. 1, ow of oil through the hollow metering valve I1 with its spiral slot i8, the outlet being indicated at I 9. u

The speed responsive means for rotating the valve l1, and thereby varying the position of the spiral slot Il with respectto the longitudinal slot Il, is shown as including a Icentrifugal governor including a spring 2l and weighted links 26, 2l pivotally suspended from a collar 28 movable along a spline or groove ,29 on the engine driven shaft 30, whenever the speed of said shaft 30 increases or decreases, the movement being down f for Yan increase (due'toA the link action under centrifugal force), and up for a decrease (due' to the spring 24) the lower collar 3l being held (by set screw 32) against any movement whatever relative to shaft 3Q.

The means for converting the occasional longitudinal movement of collar 26 into a corresponding occasional movement of valve H includes a torsion spring 5i, and a pair of abutting truncated sleeves 36 and 31, the former'being rotatable by said spring 5l in relation to shaft 30 .(such relative rotation being facilitated by bearing 38) and the latter being held against rotation (as by restraining means 46 registering with spline 44) `uut movable longitudinally to the same extent as collar 28, and in response to longitudinal movement of said collar by virtue of the interlocking flanges 4I and 42 on the said parts 28 and 31--the ange 42 being held to the sleeve 31 by suitable means 43.

The above described restraining means 46 is located on a depending arm 41 of the housing 48 in which the meshing gears 49, 50 are enclosed, as well as the torsion spring 5I whose outer end is anchored to the housing by means 52, and Whose inner end attaches to the neck portion 53 of a short shaft 54 integral-With sleeve 36 and thereby acts to hold the latter firmly abutting the truncated surface of .sleeve 31 at all times, the direction of coiling of the spring being such that. the spring unwinds as sleeve 31 descends, and rewinds as sleeve 31 forcibly turns the sleeve 36 in a reverse direction as it ascends. These alternate clockwise and counterclockwise movements (occurring as the engine speed alternately rises and falls) are effective -to rotate gears 49, 50, 10 and 1l, the latter being secured to the stem 12 of valve l1, as indicated at 13. A similar' fastening means 16 holds gear 'l0 to the shaft 11 drivably connecting gears 50 and 10 and journaled in the bosses 13 and 19 of housing 48. l

It will be seen from the foregoing that a variation in the speed of the engine tobe controlled will produce a corresponding variation in the position of the governor sleeve 31 with respect` to the sleeve 36, and hence a corresponding change in the position of the spiral slot I8 with respect to the longitudinal slot I4 of the .'servomotor, which change in position will produce an opening for the escape of fluid from the cor.-

responding side of the cylinder 48 and hence an unbalancing ,of the pressures on the opposite sides of the piston Il. This unbalancing of the pressures will in turn cause the piston Il to move to a new position in which the ilow of iluid from the cylinder will again be cut off and equilibrium reestablished-the movement of the piston being meanwhile communicated to the fuel or energy input mechanism (not shown) with whichrthe' piston rod 8 operatively connects.

What is claimed is:

In a control apparatus, in combination, a cylinder having an inlet for uid under pressure, a piston in said cylinder adapted to be moved rst in one direction and then the other by the tluid pressure in the cylinder to actuat the device to be controlled, and speed responsive means to provide and adjustably locate a iiuid outlet from the cylinder, whereby the position of the piston in the .cylinder is determined, Said speed responsive means being operable independently of said fluid under pressure and including a valve normally in flow inhibiting relation to said piston and cylinder but rotatable to connect one side or the other of said piston with said uid outlet, according to the direction of rotation of said valve, saidv speed responsive means also including a, centrifugal governor, all elements of which are mechanically separate from said piston, to prevent movements ofthe latter from being mechanically transmitted to said governor.

CHARLES I. Mcrmm MELVIN E. LoNGFEmoW. 

